Bodycount

Simple - get 1000 online kills. This, however, is not 'Seriously' Lite.

Kills in co-op sieges count towards this total. If you do the sieges and succeed in all of them, you will have many of the kills you need. Since you will likely fail them a couple of times (kills count even if you fail the siege), you will almost certainly get this. I got it at the end of my second siege (after failing the first a bunch of times).

Ok as the cheevo description says you must get 1000kills in any multiplayer gametype. Kills are acumaltive and luckily do not have to be done in 1 session like the 50/100 kill cheevos.
Kills count for:
Deathmatch
Team deathmatch
Coop (siege)

Kills will not count in private matches.

The quickest way to get these kills is to play siege maps in coop. Personally if i managed to complete all 20 waves i would average 250kills.

Even if you fail the siege map the kills will still count towards your 1000.

To check how many kills you have, while in the lobby press X to view leaderboards, change filter to friends only and look up you kill/death ratio. Total body count is NOT the correct kill count.

You will not get the cheevo when you hit the 1000kills, instead the cheevo will pop when you finish the siege map.

This achievement requires you to amass 1000 kills online. They can be done in either multiplayer or co-op, but they CANNOT be done in private matches.

The easiest and quickest way is to get a friend and go into co-op matchmaking and set the map to Pirate Bay. Use the guide for that map above, and let one person rack up all the kills. Each game, if one person gets all the kills, will net you around 350 kills alone. Do the math, and that is four games. After doing all four sieges however, you should already be at around 500 total.

You can check how many kills you have by pressing X in the multiplayer lobby to access leaderboards, then changing the leaderboards option to “Kill/death ratio,” then going down and changing the view mode to “Find you.”